Tumor Necrosis Factor (TNF) and interleukin-1 (IL-1) have been associated with a wide range of biological processes, including inflammation. Recruitment of immune cells to sites of injury involves the concerted interactions of a large number of soluble mediators, and several cytokines appear to play key roles in these processes, particularly IL-1 and TNF. Both of these cytokines are derived from mononuclear cells and macrophages, along with other cell types. IL-1 and TNF produce many of the same proinflammatory responses, including fever, sleep and anorexia, mobilization and activation of polymorphonuclear leukocytes, induction of cyclooxygenase and lipoxygenase enzymes, increase in adhesion molecule expression, activation of B-cells, T-cells and natural killer cells, and stimulation of production of other cytokines. IL-1 and TNF also contribute to the tissue degeneration arising from chronic inflammatory conditions, such as stimulation of fibroblast proliferation and induction of collagenase. These cytokines have also been implicated in the process of bone resorption and adipose tissue regulation. Thus, IL-1 and TNF play key roles in a large number of pathological conditions, including rheumatoid arthritis, inflammatory bowel disease, diabetes, obesity, bone mass loss, cancer, neurological conditions such as ischemic stroke or closed head injuries
NF-κB is a heterodimeric transcription transcription factor regulating the expression of multiple inflammatory genes. The expression of more than 70 known proteins is transcriptionally regulated by the binding of NF-κB to specific sequence elements in the promoter region of these genes (Baeuerle and Baichwal, Advances in Immunology 65:111–137, 1997) NF-κB has been implicated in many pathophysiologic processes including angiogenesis (Koch et al., Nature 376:517–519, 1995), atherosclerosis (Brand et al., J Clin Inv. 97:1715–1722, 1996), endotoxic shock and sepsis (Bohrer et al., J. Clin. Inv. 100: 972–985, 1997), inflammatory bowel disease (Panes et al., Am J. Physiol. 269:H1955–H1964, 1995), ischemia/reperfusion injury (Zwacka et al., Nature Medicine 4: 698–704, 1998), and allergic lung inflammation (Gosset et al., Int Arch Allergy Immunol. 106: 69–77, 1995). Many immune and inflammatory mediators including TNF.alpha., lipopolysaccharide (LPS), IL-1, anti-CD28, CD40L, FasL, viral infection, and oxidative stress have been shown to lead to NF-κB activation. Because of the central role of NF-κB in inflammatory disease, inhibition of NF-κB by targeting regulatory proteins in the NF-κB activation pathway represents an attractive strategy for generating anti-inflammatory therapeutics.
The IκB kinases (IKKs) are key regulatory signaling molecules coordinating the activation of NF-κB. The NFκB heterodimer in its active state is held in the cytoplasm by association with inhibitory IκB proteins (Huxford et al. Cell, 95, 759 (1998); Jacobs et al. Cell, 95, 749 (1998)). Treatment of cells with IL-1 or TNF leads to activation of intracellular signal transduction pathways that in turn lead to phosphorylation of IκB proteins on specific amino acid residues (serines 32 and 36 in IκBα, serines 19 and 23 in IκB β). Mutation of one or both serine residues renders IκB resistant to cytokine-induced phosphorylation. This signal-induced phosphorylation targets IκB for proteosome-mediated degradation, allowing nuclear translocation of NF-κB (Thanos and Maniatis, Cell, 80, 529 (1995)). The only regulated step in the IκB degradation pathway is the phosphorylation of IκB by IκB (IKK) kinases (Yaron et al. EMBO J. 16, 6486 (1997)).
The kinases IKKα and IKKβ have been identified as the most likely mediators of TNF- and IL-1-induced IκB phosphorylation and degradation, which results in NF-κB activation and upregulation of families of genes involved in inflammatory processes (Woronicz et al. Science (1997); Karin, Oncogene 18, 6867 (1999); Karin, J. Biol. Chem. 274, 27339 (1999)). IKKα and IKKβ have very similar primary structures, displaying more than 50% overall sequence identity. In the kinase domain, their sequences are 65% identical.
Because of the important role played by TNF and IL-1 in many pathological conditions, and the involvement of IKKα and IKKβ in the signal transduction of both TNF and IL-1, there is a need for compounds that potently and selectively inhibit either of these IKK kinases, as well as treatments or therapies using such compounds. The present invention satisfies these needs.